Method of and machine for stretching leather



N. FRIED 2,125,223 I METHOD OF AND MACHINE FOR STRETCHING LEATHER v Jul 26, 1938.

Filed Jan. 25, 1957 s Sheets-Sheet 1 July 26,1938. N. FRIED METHOD OF AND MACHINE EOR STRETCHING LEATHER Filed Jan. 25, 1937 5 Sheets-Sheet 2 o0 orwoomouqo T SW EATHER 5 Sheets-Sheet 3 July 26, 1938. N. FRIED Z METHOD OF AND MACHINE FOR STRETCHING L Filed J n. 25, 1937 W .Fw R

i Patented July 26, 1938 PATENT OFFICE METHOD OF AND MACHINE FOR STRETCH- ING LEATHER Nathan Fried, New York, N. Y., assignor to Johnson Belting Company, New York, N. Y., a corporation of New York Application January 23, 1937, Serial No. 122,073

) 12 Claims.

, This invention relates to methods of, and machines for stretching leather while it is in a wet or moist or .sammied condition. Such leather is otherwise in a finished condition, but for some uses it requires stretching and drying before it is sold for commercial use. For some uses, the moist leather need be but moderately stretched for ultimate use, for example for use in shoe manufacture; whereas for other uses, for example for use as power belting, for which purpose leather stretched and dried as described herein is particularly adapted, the leather should be stretched until all possible stretch has been removed, and dried while still mounted in an intensely stretched condition on the stretching machine, tension stress being constantly maintained on the leather and thereby further elongating the same during the drying until it is bone dry". When the finished leather is to be used in making the better-grades of belting, leather known in the trade as Butt Bends is used, although any kind of moist or wet leather maybe stretched and dried on the stretching machine described herein.

The presentinvention has for an object to provide a process of and machine for stretching moist or wet or sammied'leather and drying the same while under a continuously maintained intense stretching stress until it has become "bone dry and acquired a permanent set, and for practical purposes is thereafter non-extensible in use. A further object is to provide leather which will not stretch further even when'subjected to continuous severe strains under changeable atmospheric conditions for long periods of time, for. example, leather for use as power belting. Other objects of the invention will be apparent to those skilied. in this art upon reading the specification. y

In the accompanying drawings:

Figure 1 illustrates a top plan view of the clamp engaging the side members, shown as.

channel bars, of the stretching frame, and bolts to secure the shoes" to the side members:

Figure 4 is a view resembling Figure 1, with leather mounted and clamped thereto;

Figure 5 is a side view of the frame with leather mounted thereon, the leather about to be subjected to the stretching process, with the pushleather in the process of being stretched, with' the ,axis of the "pushing and pulling machine in a reversed position when compared with Figure 5, and the side members of the frame flexed;

Figure '7 resembles Figure 6, with the pushing and pulling machine detached, and with bolts in place securing the adjustable clamp to the side members of the frame;

Figure 8 shows the frame and the leather thereon after it has been stretched and dried and the previously flexed side members of the frame returned to their normal straight position, and the bolts which secure the adjustable clamp still in place; the stretched and dried leather may now be removed from the stretching frame after removing the bolts;

Figure 9 is an enlarged side view of the fixed clamp bar showing a clamp lug in place pressing the edge of the butt end of the leather into a clamp groove, and also an end of the lug engaging one of the grooves;

Figure 10 is an enlarged side view of the adjustable clamp with the clamp bar in place, and one edge of the bar pressing the edge of the leather into a clamp groove, and also showing a section of a Fshoe" on one of the side members of the frame;

Figure 11 is a view in perspective of a clamp lug used to secure the butt end of the leather to the fixed clamp;

Figure 12 is a view in perspectiveof the clamp bar used to secure the edge of the leather to the adjustable clamp;

Figure 13 is a view in perspective of a suitable type of bolt and nut used to secure the adjustable clamp to the frame;

Figure 14 is a plan view of a suitable type of bolt, used to'secure the clamp lugs and clamp bar to the leather holding clamps;

Figure 15 is a plan view of a modified type of leather stretching frame in which the side flexible members are swivelled at the ends of the frame by suitable bolts or pins; the adjustable clamp is shown, and also the T rails upon which" the adjustable clamp moves and to which the adjustable clamp is to be secured;

Figure 16 is a side view of Figure 15, showing the swivelled bolt joints attaching the side members to the clamps, and also showingthe T rail with the adjustable clamp thereon;

Figure 17 is an end view of Figure 15 at the bottom, showing the adjustable clamp mounted upon the T rails, and also showing metal blocks in the ends of the side members;

Figure 18 is a plan view of the leather stretching frame shown in Figure '15, with; leather mounted and stretched thereon, and showing the I side members flexed outwards;

Figure 19 is a side view of Figure 18 with the mounted leather and the adjustable clamp secured to the T rail;

Figure 20 is a broken view, in perspective, ,of

a side member, shown as a channel bar, with metal blocks welded in the ends; and- Figure 21 shows, in section, a pair of suitable angle bars which may be used as side members in the place of channel bars.

The stretching frame I, described herein and illustrated in' Figures 1, 2, 3, and 4, consists of functioning stiff but flexible and elastic tensionmaintaining members may be used, for example the angle bars 28, Figure 21. The upper face of the clamping bar 3 is provided with leather engaging and lug engaging means, preferably triangular grooves 5, and transverse slots 6 through which latter are to be passed suitable bolts. 1, Figure 14. To the upper ends of the flexible members orchannel bars 2, 2, are welded the supporting members 8 between the outer ends of which is secured a suitable roller 9 by which the frame I with stretched moist or sammied" leather thereon is later suspended on a trolley, not shown; any other means for suspending the frame may be used. To the lower ends of the channel bars 2, 2, is welded or otherwise secured. a cross bar III which maintains the channel bars spaced and stifiens the frame. The side walls of the channel bars are perforated at Figure 2, through which are later passed the bolts l2, Figure '13. Mounted upon the frame I is the adjustable clamp ridge bar'l3, consisting of a clamp ridge or channel shaped bar I4, Figure 10, and welded to the clamp ridge I4 are suitable channel shaped sliding members or shoes 5, Figures 2, 3, 5, and 10, each shoe embracing a channel bar, the sides of the shoes being perforated as at it, Figure 2. The surface of the clamp ridge I4 is provided with triangular grooves I and bolt holes l8, Figure 2, through which lat-' ter are to be passed bolts l8, Figure 10, similar to bolts 1. Uponthe adjustable clamp ridge I4 is to be mountedaclamp bar 20, Figure 12, provided with a pointed edge 2|, and bolt holes 22, to receive the bolts l8. .To one face of the clamp ridge I4 is secured by weldingor otherwise the member 23 provided with the hook 24, by which the clamp ridge bar I: with the leather clamped thereto by clamp bar 20 is drawn bya suitable stress and pressure" or pulling and pushing machine, illustrated diagrammatically by. the pivoted lever 25, pulling chain 26, and thrust member 21, shown in Figures 5 and 6; the thrust member 21 presses against the ends of the channel bars 2, 2, at the adjustable clamp end while the chain 25 pulls the clamp ridge bar l3 and stretches the leather, Elgurefi.

In securing wet or moist or sammied leather 30 to the stretching frame I, it is mounted thereon while the latter is in a horizontal posi tlon,-and the butt end 3| of the leather, which on the piece illustrated in Figure 4, to be stretched, and which has an irre lar outline, is secured to the fixed clamp bar 3, gures 4 and 9, by means of the several lugs 32, Figure 11, each of which engages the'edge of the leather and is thereafter bolted down to the fixed clamp 3 by the bolts l which latter pass through the slots 6 and through the lugs 32; each lug is provided with pointed edges 34, pointed edge 34 presses the edge 3| of the leather into a triangular groove 5 while the other edge 35 engages another groove, Figure 9; the lugs 32 are wider than the slots 6, and securely hold the leather. to the clamp 3. The other end 36 of the leather is then secured to the clamp ridge 14 by the clamp bar 20 which latter has a triangular edge 2|, and is bolted to the adjustable clampridge H by the bolts IS, the edge 2| pressing the edge 36 of the leather into a groove ll, Figure 10, thereby firmly securing it at this end. Suitable timbers 40 are then placed beneath the leather,

Figure 5, and the leather then pulled from both sides to straighten it, the leather is then nailed or otherwise secured to the timbers to maintain it straight and flat.

After the leather has been secured to the stretching frame, the latter is then connected to the pulling and pushing" machine, illustrated diagrammatically by the inclined lever 25 in Figures 5 and 6, the chain 26 being connected to the hook 24, and the thrust'member 21 being placed against the ends 'of the channel bars ,2,

2; the pulling and pushing machine lever 25 is nextoperated, pulling the adjustable clamp l3 by the chain 26 and stretching or preliminarily elongating the leather while a corresponding thrust stress is applied to the channel bars 2, 2,

as illustrated inv Figure-6 by the thrust member 21, and as illustrated, by the reversed positionof the lever 25 when compared with its position in Figure 5; the cooperating stresses storing elastic .energy in the frame by flexing the channel bars, Figure 6, the stress applied varying with the characteristics of the leather being stretched,

the kind of leather, its width, and thickness; the stress applied to the leather is equal to the pressure applied to the flexed channel bars, and may be as high as, or exceed, 10,000 pounds per foot of width of the leather, the total applied 7 stress varying from about 35,000 pounds. to about 50,000 pounds, according to its characteristics as above noted, and to the use to which the finished leather is to be applied; for power belting, V

stresses of about 10,000 pounds per foot of width of leather according to, its characteristics are generally used. After a sufficient amount of stress has been applied and the leather preliminarily elongated, Figure 6, the adjustable clamp I3 is secured in placev by inserting bolts, I2 through the alined holes l6 and H in the shoes I5 and channel bars 2, Figures 3 and 7, the pulling and pushing machine 25 released and the chain 26 detachedfrom the hook 24; the frame with the moist stretched and elongated leather thereon is next mounted upon a trolley (not shown), and the leather subjected to continuous currents of drying air preferably from above of thrust or pressure exerted upon the channel bars 2, which thrust or pressure flexes the channel bars as shown in Figures 6 and 7; the flexed frame functions as a composite spring and maintains the leather under constant severe tension during the drying, and in the process of drying the leather is further automatically stretched and elongated by an amount corresponding approximately to the amount of the stored elastic energy in the flexed channel bars, the additional lengthening of the leather under this constant stress permitting. the flexed channel bars or flexed spring-like members to straighten while still maintaining a severe stress on the leather until it is ready to be removed from the frame, as shown in Figure 8.

The modified stretching frame 50, shown in Figures 15 to 20, is based upon the same principle of flexing the flexible members or channel bars as that illustrated in Figures 1 to 8. The frame 50 also consists of a pair of parallel, stiff, flexible and elastic tension-maintaining steel members, which may be channel bars 5|, 5!, or may have any other suitable shape, for example the angle bars 28, Figure 21, and which are arranged to be flexed outwards as shown in Figure 18. The channel bars 5|, 5|, are provided with welded steel blocks 56, Figure 20, the ends of the channel bars and the blocks having bolt holes 5?.

Figures 1 to 5. The lower ends of the channel bars i, 5!, are also connected by swivelled joints to a clamp plate 53 by bolts 59. The clamp plate 53 has preferably a smooth surface upon which are secured as by welding, suitable T-rails 55, Figures 15 to 19, which are provided with holes 60; above the T-rails 54 is a clamp ridge block M, Figures 16 and 19, (otherwise similar to that 1 shown inFigures l to 8) and to the lower surface of the clamp ridge block are secured, as by welding, the shoes" 55 which ride upon, and are adapted to be secured to, the T-rails .56 by the bolts i? which pass through cooperating holes in the shoes and the T-rails,Figures l7 and 19. The clamp ridge block 95 is provided with grooves and a clamp bar 2b, as in Figure 10, by means of which the other or straight. end of the leather at is secured, as in Figures t and 5.. The frame 5b is also provided with a suitable suspension means, such as pulley t, and also a hook M, as described in Figures 1 to 8. To mount the leather hi, the butt end is secured to theupper clamp 52, as in Figures 1 to 5, the adjustable clamp then moved forwards on the T-rails 54, Figure 16, the straight end of the leather then secured to the adjustable clamp, the timbers 80 then nailed 'thereto asdescribed above, and the frame 50 with the wet, moist, or sammied leather thereon then connectd to the pulling and pushing machine 25 as described under Figures 5 and 6. Upon operating the, machine 25 the wet leather will be stretched and a corresponding thrust applied to the ends of the channel bars 5i flexing the channel bars outwards as shown in Figure 18, until a desired degree of tension has been applied to the leather. During the stretching, the adjustable clamp and shoes 55 will move backwards upon the T-rails 54, Figures 18 and 19, and after a desired degree of tension has been appliedto the leather 6 I, with a corresponding outward-flexing of the channel bars, gure 18, the bolts l2 are passed through the shoes 55 and 4 T-rails 54, Figure 17, securing the stretched leather to the frame 50, Figure 18. The frame with the mounted stretched wet leather 6| is then placed on a trolley, (not shown), and subjected to the current of drying air as described above. During the drying, the flexed channel bars 5|, Figure 18, will maintain the leather stretched, and automatically further stretch the same as described above, the channel bars finally leather stretched and dried as described herein show a pronounced practically parallel arrangement, whereas in a corresponding section of a dry but unstretched piece of leather the fibres are anything but parallel. Belts made from leather stretched and dried as described herein after having been subjected to severe service driving heavy machinery did not stretch in use and did not require any shortening over a period of eighteen months, whereas belts made from leather stretched and dried' by standard processes in general use and subjected to the same severe service for the same period of time required shortening twice.

I claim 1. A leather stretching frame comprising flexible, elastic, tension-maintaining leather stretching longitudinal members, cooperating transverse clamping members, one of said clamping members consistingcf a fixed clamp device at one end of said frame, another of said clamping members consisting of an adjustable clamp device at the other end of said frame, and means to secure the adjustable clamp device in a selected location on said frame.

2. A leather stretching frame as in claim 1, in which the flexible, elastic, tension-maintaining leather stretching members are constructed to hex under stress and to regain their normal position when the stretching stress is removed, leather holding clamps, and means to adjustably connect said members when in a flexed condition to one of said clamps.

3. A leather stretching frame as in claim 1, in which the flexible, elastic, tension-maintaining leather stretching members are channel bars.

t. A leather stretching frame, as in claim 1, in which the flexible, elastic, tension-maintaining leather stretching members are channel bars, and the fixed clamp device is provided with leather engaging grooves and slots.

5. A leather stretching frame as in claim 1, in which the flexible, elastic, tension-maintaining leather stretching members are channel bars, and the adjustable clamp device is provided with leather engagin grooves and bolt openings, and

- sliding members adapted to engage said channel ing members, a fixed clamp device at one end of 'said frame, said clamp device provided with leather engaging grooves, slots in said clainp device, clamp lugs, said lugs provided with ends one of which is adapted to engage one of said grooves, and the other end adapted to press and secure leather in another or said grooves, and means to secure said lugsto said clamp device.

7. A leather stretching frame comprising :flexible, elastic, tension-maintaining leather stretching members, a fixed clamp at one end of said frame, an adjustable clamp device at the other end of said frame, said clamps provided with leather engaging grooves, a clamp barfor said adjustable clamp, said clamp bar provided with an edge adapted to press and secure leather in one of said grooves, means to secure said clamp bar to said adjustable clamp, sliding members secured to said adjustable clamp and constructed to engage said stretching members, and means to secure said sliding members to said stretching members in a selected location.

8. A leather stretching frame comprising flexible, elastic, tension-maintaining leather stretching channel bars, a. fixed clamp device at one: end of said frame, an adjustabie clamp device at the other end of said frame, said clamps provided with leather engaging grooves, clamp lugs for the fixed clamp, a clamp bar for the adjustable clamp, said clamp lugs and clamp bar each provided with an edge adapted to press and'secure leather in a leather engaging groove, means to secure said clamp bar to said adjustable clamp, a hook on said adjustable clamp, sliding members secured to said adjustable clamp and constructedto engagesaid channel bars, and means to secure said sliding members to said channel bars.

' 9. A leather stretching frame comprising flex- 1 ible, elastic, tension-maintaining leather stretching channel bars, a fixed clamp device at one end of saidframe, slots in said fixed clarnm an adjustable clamp device at the other end of said frame, each of said clamp devices provided with ,leather engaging grooves, clamp lugs, said .clamp clamp bar for said adjustable clamp, said clamp bar provided with an edge adapted to press and secure leather in a groove in said adjustable clamp, means to secure said clamp bar to said adjustable clamp, a hooE-zon said adjustable clamp, sliding members secured to said adjustable clamp and constructed to engage said channel bars, and means to secure said sliding membars to said channel bars.

10. The method ofdeveloping a permanent set in leatherduring the drying thereof, which comprises applying a tensile stress of approximately 10,000 pounds per foot of width of the leather while it is in a wet or moist or sammied condition according to the characteristics and thickness of the leather, thereby preliminarily elongating said sammied leather, subjecting said pre-elongated sammied leather to the drying action of currents of air and further continuouslyelbngating the sammied leather by maintaining an intense stretching stress thereon during the drying, and continuing the intense stretching and air drying until said leather is dry.

ii. The method of stretching wet or moist or fsamrnied leather, which comprises mounting said wet or moist or sammied ieather upon a stretching irame, preliminarily elongating said mounted leather by a stretching stress upwards to 10,00ii pounds per foot of width of the leather according to the characteristics and thickness of the leather and also storing elastic energy in said frame, drying the pre-elongated sammied leather while mounted and further elongating the are-elongated leather by the stretching stress exerted by the liberation of the stored elastic energy during the drying.

12. In the method of stretching wet or moist sammied leather, the step of still further increasing the length of the prestretched sam- ,mied leather by the continuous application of an intense stretching stress thereon of initially approximately 8,000 pounds and above per foot of width according to the characteristics and thickness of the leather and progressively elon gating said leather thereby during the drying and until dry.

NATHAN FRIED. 

